Let x0 of type ι be given.
Let x1 of type ι be given.
Let x2 of type ι be given.
Let x3 of type ι be given.
Let x4 of type ι be given.
Let x5 of type ι be given.
Apply binunionI1 with
SetAdjoin (SetAdjoin (SetAdjoin (UPair x0 x1) x2) x3) x4,
Sing x5,
x2.
The subproof is completed by applying unknownprop_d01b6855d365ef88e4dec58ef26d87a9fb41a039e0ffb88e5b1374db5dfc773b with x0, x1, x2, x3, x4.